The prior art is replete with a wide variety of different types of formulations and allusion to the problems created with their use. For example, the nearest approach of which we are aware involves wiping the surface to be cleaned with a cloth on which a solvent; such as methyl ethyl ketone; or a solvent blend, or formulation, such as methyl ethyl ketone, aromatic naptha, isopropyl alcohol, and ethyl acetate has been applied. Other solvent blends that include chlorofluorocarbons and trichloroethane are also used. The wipe cloths are then open to the atmosphere or are transferred to a metal can for temporary storage. The cloths then go through several stages of transfer and storage until they are eventually laundered, buried as a solid waste or incinerated.
Alternatively, the wiping operation is performed or the cloths stored in an enclosed area equipped with forced ventilation and a carbon absorption system. The solvent vapors from the surfaces being cleaned and from the used wipe cloths are carried into the filtration media where they are partially absorbed. Periodically the solvents are stripped from the carbon and are incinerated.
Several disadvantages are inherent in these prior art type systems and deleterious effects result therefrom. Using the first approach, the solvents evaporate rapidly from the work piece during the wiping operation and further evaporation takes place from the solvent-laden wipe cloths during storage and transfer prior to their final disposal. The emissions from certain solvents eventually reach the atmosphere where they react with other air emissions in the presence of sunlight to form ozone and/or create smog.
Alternatively, certain other solvent emissions will reach the stratosphere where they deplete the protective ozone layer, causing extensive damage to animal and plant life on earth. These solvents are primarily chlorofluorocarbons and trichloroethane. There are federal, state and local regulations that restrict volatile emissions from cleaning operations and violations can lead to severe penalties including fines, incarceration of managing personnel, and shut down of the offending facility.
Many of these solvents have been banned by federal statute. The federal statute entitled "Clean Air Act" was passed by Congress in 1990 and signed into law. This law curtails the use of such common solvent cleaners as chloroform, dichloromethane, methyl ethyl ketone, methyl isobutyl ketone, toluene, trichloroethylene, trichloroethane and xylenes. A formulation which contains none of these curtailed ingredients but which are efficient cleaners and have low flammability, low toxicity and slow evaporation rates should have wide acceptance in many industries.
The carbon absorption system for collection and disposal of wipe solvents has other disadvantages. It is expensive to install and to operate and has limited collection efficiency and capacity. Moreover, such a system is not feasible in large facilities where cleaning operations are required in widely scattered locations, but requires rather closely located areas and a central facility.
This invention overcomes these disadvantages and deleterious effects. Specifically, it is desirable that a cleaning formulation have the following features:
1. The formulation should achieve superior cleaning with a considerable reduction of volatile emissions to the atmosphere.
2. The formulation should have excellent cleaning efficiency for a wide variety of soils.
3. The cleaning formulation should have a low evaporation rate, low toxicity, and be nonflammable; for example, as demonstrated by having a flash point of 100 degrees Fahrenheit or higher when measured by the closed cup method.
In addition, the method of disposing of cloths soaked in the formulation should be adequate to keep the emissions to the atmosphere low.